Dual-homing protection of a network device node is a network data backup method in which a network node is connected to two different network devices in another network area by using two links: an active link and a standby link, and network reliability is improved by means of mutual backup protection of the active link and the standby link. In the prior art, TYPE B and TYPE C/TYPE D protection technologies of extension lines are generally used to implement dual-homing protection of a node.
In TYPE B, network data backup is implemented by protecting active and standby PON ports of an OLT and active and standby optical fibers; and in TYPE C/TYPE D, network data backup is implemented by using two PON ports of the OLT, two PON ports of an ONU, and by dual redundancy of fiber trunks, optical splitters, and distributor fibers. Specific implementation manners of TYPE C/TYPE D include two types: protection of different PON MAC chips on a same PON board of the OLT, and protection of PON ports between PON boards.
In addition, the prior art provides a VALN-based Ethernet linear protection switching mechanism, namely, G.8031, where the protection switching mechanism is implemented by means of the APS (Automatic Protection Switching) protocol. The APS protocol is a protocol, specified in G.8031, that switching results of devices at two ends keep consistent in bidirectional protection switching, and an APS protocol packet can be sent only on a protection channel, but cannot be transferred on a working channel.
In the prior art, a segment protection scheme of G.8031 and TYPE B/C protection is used to implement network data backup, that is, OLT GE uplink dual-homing protection can be implemented by using G.8031 from the OLT to a CP, and an end-to-end service path is protected by means of G.8031 VLAN service channel protection; in addition, TYPE B and TYPE C dual-homing protection schemes are used in a PON, and a PON fiber trunk is protected by using a PON link level, thereby implementing network data backup.
However, in the segment protection scheme of G.8031 and TYPE B/C protection, according to definitions in the G.8031 standards, only two VLAN service channels, VLAN X and VLAN Y, that protect each other can be established between one OLT and a remote switch device ETH Switch, where the VLAN X is an active service channel and the VLAN Y is a backup service channel. When a fault occurs on the active service channel VLAN X, a service is switched to the backup service channel VLAN Y, so as to ensure that a service accessed by an ONT is normal. However, when a fault occurs on a PON between the ONT and one OLT, another OLT serves as a standby OLT and enables a PON port between the standby OLT and the ONT by means of dual-homing TYPE B protection, which allows a service on the ONT corresponding to the faulty PON to access a network by using the standby OLT. However, because the backup service channel VLAN Y is established on the ONT corresponding to the faulty PON, the standby OLT cannot perform G.8031 VLAN protection switching, and service interruption of an uplink Switch link cannot be notified to a PON side, so that linkage switching of the service on the PON side cannot be implemented; and disconnection of a PON can neither be associated with uplink link switching of a CP side, thereby resulting in interruption of the service accessed by the ONT. As a result, when the segment protection scheme is used in the uplink of the OLT, due to different protection schemes, deployment by a user is complex, end-to-end switching in a system is unpredictable, and real cross-device end-to-end service level switching cannot be implemented rapidly.